1. Field of the Invention
The present invention relates to a lubricating oil composition for chains and more particularly to such a lubricating oil composition which is adapted to be used at a high temperature of 150.degree. C. or above.
2. Prior Art
In the step of molding glass fibers, baking bread, baking coating materials applied to automobiles, or the like, a large-sized chain is generally used for a conveyor for sending the objects to be treated into a heating oven and a part of the chain enters the oven so very often it is exposed to a high temperature of 150.degree. C. or above.
Conventional lubricating oils are unsuitable for use as lubricating oils used at such a high temperature and therefore a dispersion of graphite in a solvent such as triethylene glycol has instead been used as the latter lubricating oil. However, solvents such as triethylene glycol only function as a dispersant for graphite and will soon be lost by evaporation and/or thermal decomposition as soon as a lubricated chain enters into a high-temperature atmosphere such as a heating oven, if the solvents are used with graphite to form a lubricant for the chain. Accordingly, it is only graphite in this lubricant that substantially acts as a lubricant.
In the case when such a lubricant is used in such a chain, the graphite merely adheres to the surface of the chain and is therefore apt to be removable from it, thus requiring a more frequent supply of the lubricant. Further, this raises problems because the heating oven in which the chain has entered is filled with vapors of the solvent and thermal decomposition products aggravate the working environment and the exhaustion of the vapors into the atmosphere causes environmental pollution.